There is a proposal to arrange a ROM (Read Only Memory) on a head substrate integrated on an inkjet printhead (to be referred to as a printhead hereinafter) included in a recent inkjet printing apparatus (to be referred to as a printing apparatus hereinafter) to freely read out or hold information (individual information) unique to the head, including the ID (Identify) code of the printhead itself and the driving characteristic of the ink discharge mechanism.
In an arrangement using a printhead detachable from a printing apparatus main body, this approach is especially effective in acquiring information unique to the printhead. Patent reference 1 discloses arranging an EEPROM (Electrically Erasable Programmable ROM) in a printhead.
In another known method, a resistance indicating information unique to a head is formed on the base substrate of a head substrate together with the layer films of, e.g., an ink discharge mechanism. This approach is effective when the amount of information to be held in the printhead is relatively small. This method also allows a printing apparatus to obtain information unique to the printhead by reading the value of the resistance formed on the base substrate. The printing apparatus is capable of optimum driving for ink discharge based on the information.
Patent reference 2 discloses forming, on a base substrate used for manufacturing a head substrate, a fuse serving as a ROM (to be referred to as a fuse ROM hereinafter) simultaneously together with the layer films of, e.g., an ink discharge mechanism. When the fuse ROM is selectively melted under the control of a simultaneously formed logic circuit, the fuse RON can hold binary data based on the presence/absence of the fuse.
A printhead having the above-described head substrate can simplify the structure, improve the productivity, reduce the cost, and reduce the weight and size while holding the information unique to the head.
Patent reference 1: Japanese Patent Publication Laid-Open No. 3-126560
Patent reference 2: Japanese Patent Publication No. 3428683